These are the contexts of the quotes tweeted from @sueannbowling between August 28 and September 3, 2014. The first six are from The Two Towers, by J.R.R. Tolkien.
“The guest who has escaped by the roof will think twice before he comes back in by the door.” Gandalf, when Saruman tries to invite him back into Orthanc.
“He cannot be both tyrant and counselor.” Gandalf, speaking of Saruman at Orthanc.
“I grieve that so much that was good now festers in the tower.” Gandalf, after Saruman has refused to work with them, and chosen instead to remain a prisoner in Orthanc. This is from the book, not the movie.
“Do not meddle in the affairs of wizards, for they are subtle and quick to anger.” Gildor’s saying, quoted by Merry to Pippin when Pippin is curious about the palantir.
“Do not then stumble at the end of the road.” Gandalf’s advice to Aragorn as he gives him the palantir.
“I took a fresh look at the consequences of what I believe, and I didn’t like what I saw.” Sue Ann Bowling, Tourist Trap. Penny’s thought, after a discussion with Roi on the effects of a local law she had taken for granted.